[PATCH v4 02/10] powerpc/kvm: make hypervisor state restore a function
From: Shreyas B. Prabhu <hidden>
Date: 2016-05-24 13:15:37
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
In the current code, when the thread wakes up in reset vector, some
of the state restore code and check for whether a thread needs to
branch to kvm is duplicated. Reorder the code such that this
duplication is avoided.
At a higher level this is what the change looks like-
Before this patch -
power7_wakeup_tb_loss:
restore hypervisor state
if (thread needed by kvm)
goto kvm_start_guest
restore nvgprs, cr, pc
rfid to process context
power7_wakeup_loss:
restore nvgprs, cr, pc
rfid to process context
reset vector:
if (waking from deep idle states)
goto power7_wakeup_tb_loss
else
if (thread needed by kvm)
goto kvm_start_guest
goto power7_wakeup_loss
After this patch -
power7_wakeup_tb_loss:
restore hypervisor state
return
power7_restore_hyp_resource():
if (waking from deep idle states)
goto power7_wakeup_tb_loss
return
power7_wakeup_loss:
restore nvgprs, cr, pc
rfid to process context
reset vector:
power7_restore_hyp_resource()
if (thread needed by kvm)
goto kvm_start_guest
goto power7_wakeup_loss
Reviewed-by: Paul Mackerras <redacted>
Reviewed-by: Gautham R. Shenoy <redacted>
Signed-off-by: Shreyas B. Prabhu <redacted>
---
- No changes in v4
Changes in v3:
=============
- Retaining GET_PACA(r13) in System Reset vector instead of moving it
to power7_restore_hyp_resource
- Added comments indicating entry conditions for power7_restore_hyp_resource
- Improved comments around return statements
arch/powerpc/kernel/exceptions-64s.S | 28 ++------------
arch/powerpc/kernel/idle_power7.S | 72 +++++++++++++++++++++---------------
2 files changed, 46 insertions(+), 54 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 4c94406..4a74d6a 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S@@ -107,25 +107,9 @@ BEGIN_FTR_SECTION beq 9f cmpwi cr3,r13,2 - - /* - * Check if last bit of HSPGR0 is set. This indicates whether we are - * waking up from winkle. - */ GET_PACA(r13) - clrldi r5,r13,63 - clrrdi r13,r13,1 - cmpwi cr4,r5,1 - mtspr SPRN_HSPRG0,r13 + bl power7_restore_hyp_resource - lbz r0,PACA_THREAD_IDLE_STATE(r13) - cmpwi cr2,r0,PNV_THREAD_NAP - bgt cr2,8f /* Either sleep or Winkle */ - - /* Waking up from nap should not cause hypervisor state loss */ - bgt cr3,. - - /* Waking up from nap */ li r0,PNV_THREAD_RUNNING stb r0,PACA_THREAD_IDLE_STATE(r13) /* Clear thread state */
@@ -143,13 +127,9 @@ BEGIN_FTR_SECTION /* Return SRR1 from power7_nap() */ mfspr r3,SPRN_SRR1 - beq cr3,2f - b power7_wakeup_noloss -2: b power7_wakeup_loss - - /* Fast Sleep wakeup on PowerNV */ -8: GET_PACA(r13) - b power7_wakeup_tb_loss + blt cr3,2f + b power7_wakeup_loss +2: b power7_wakeup_noloss 9: END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
index 705c867..d5def06 100644
--- a/arch/powerpc/kernel/idle_power7.S
+++ b/arch/powerpc/kernel/idle_power7.S@@ -276,6 +276,39 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66); \ 20: nop; +/* + * Called from reset vector. Check whether we have woken up with + * hypervisor state loss. If yes, restore hypervisor state and return + * back to reset vector. + * + * r13 - Contents of HSPRG0 + * cr3 - set to gt if waking up with partial/complete hypervisor state loss + */ +_GLOBAL(power7_restore_hyp_resource) + /* + * Check if last bit of HSPGR0 is set. This indicates whether we are + * waking up from winkle. + */ + clrldi r5,r13,63 + clrrdi r13,r13,1 + cmpwi cr4,r5,1 + mtspr SPRN_HSPRG0,r13 + + lbz r0,PACA_THREAD_IDLE_STATE(r13) + cmpwi cr2,r0,PNV_THREAD_NAP + bgt cr2,power7_wakeup_tb_loss /* Either sleep or Winkle */ + + /* + * We fall through here if PACA_THREAD_IDLE_STATE shows we are waking + * up from nap. At this stage CR3 shouldn't contains 'gt' since that + * indicates we are waking with hypervisor state loss from nap. + */ + bgt cr3,. + + blr /* Return back to System Reset vector from where + power7_restore_hyp_resource was invoked */ + + _GLOBAL(power7_wakeup_tb_loss) ld r2,PACATOC(r13); ld r1,PACAR1(r13)
@@ -284,11 +317,13 @@ _GLOBAL(power7_wakeup_tb_loss) * and they are restored before switching to the process context. Hence * until they are restored, they are free to be used. * - * Save SRR1 in a NVGPR as it might be clobbered in opal_call_realmode - * (called in CHECK_HMI_INTERRUPT). SRR1 is required to determine the - * wakeup reason if we branch to kvm_start_guest. + * Save SRR1 and LR in NVGPRs as they might be clobbered in + * opal_call_realmode (called in CHECK_HMI_INTERRUPT). SRR1 is required + * to determine the wakeup reason if we branch to kvm_start_guest. LR + * is required to return back to reset vector after hypervisor state + * restore is complete. */ - + mflr r17 mfspr r16,SPRN_SRR1 BEGIN_FTR_SECTION CHECK_HMI_INTERRUPT
@@ -438,33 +473,10 @@ common_exit: hypervisor_state_restored: - li r5,PNV_THREAD_RUNNING - stb r5,PACA_THREAD_IDLE_STATE(r13) - mtspr SPRN_SRR1,r16 -#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE - li r0,KVM_HWTHREAD_IN_KERNEL - stb r0,HSTATE_HWTHREAD_STATE(r13) - /* Order setting hwthread_state vs. testing hwthread_req */ - sync - lbz r0,HSTATE_HWTHREAD_REQ(r13) - cmpwi r0,0 - beq 6f - b kvm_start_guest -6: -#endif - - REST_NVGPRS(r1) - REST_GPR(2, r1) - ld r3,_CCR(r1) - ld r4,_MSR(r1) - ld r5,_NIP(r1) - addi r1,r1,INT_FRAME_SIZE - mtcr r3 - mfspr r3,SPRN_SRR1 /* Return SRR1 */ - mtspr SPRN_SRR1,r4 - mtspr SPRN_SRR0,r5 - rfid + mtlr r17 + blr /* Return back to System Reset vector from where + power7_restore_hyp_resource was invoked */ fastsleep_workaround_at_exit: li r3,1
--
2.4.11